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• Washing up liquid
• Glass cleaner
• A lint-free cloth or rag
• A putty knife
• A paper plate
• Acetone

You can only repair blown double glazed windows in the sense that you can replace the sealed unit (the glass part of the window) instead of having to replace the entire window.

When a double glazed window is blown, it means that the seal around the window has failed and is now letting air in and out. Often the first sign that the sealed unit has blown is condensation on the inside of the window, which is annoying since there’s no way to get rid of it! When your sealed unit has blown, you’ll be losing heat out of the window, meaning you could be spending more on your energy bills.

As a temporary fix, you could see if you can buy a misting repair kit online, but the condensation will eventually occur again as the air gets in. The best thing to do is ask a window installer or glazier to replace the sealed unit for you.

It's simple to replace the glass in a window – the specialist will remove the beading around the window, remove the blown glass from your window frame and set it to one side. They will then clean up around the frame before adding spacers in, then fitting the new sealed unit into the frame. They’ll make sure it’s a snug fit before replacing the beading back around the window to secure it.

There's no reason to put off repairing a blown double glazed window since the cost is generally much less than replacing the entire thing. A sealed unit with installation costs an average of £100, whereas a completely new window will cost around £400. You’ll soon notice that it’s less draughty and will be able see out of your window once you’ve had the blown glass replaced.

The energy efficiency of windows is measured using ratings, varying from A, the most efficient, to G, the least efficient. This scheme is run by the British Fenestration Council (BFRC). To comply with Building Regulations you’ll need windows of energy efficiency at least level C.

Double glazing frames don’t just have to come in uPVC and are available in other materials including aluminium and wood too. Wooden or timber windows are more suited to properties with a traditional look and are often the frame of choice for listed buildings and homes in conservation areas. When properly maintained wooden windows can last well for years but can be up to three times more expensive than uPVC.Aluminium is the strongest and most durable option. As a metal it is highly resistant to the UK’s changing weather conditions and won’t rust, warp, crack or peel. Aluminium offers a modern appeal and is available in a range of colours.

Removing a double glazed window can be quite labour intensive. If you decide to try it yourself, make sure you give yourself plenty of time, and wear gloves and goggles.

Begin by unscrewing all opening windows at the hinges and removing them. Then take away the beading and putty around any fixed panes and take them out too.

Once you’ve removed all the glass, use a saw to put angled cuts in the frame, and a bar and hammer to remove it in sections. You should remove the sill if you’re going to replace that too.

Finally, cut through any screws holding the frame into place with a hacksaw.

1. Using a rubber mallet and a strong pallet knife, remove the beading around the window. You might think they’re part of the frame, but they’re actually separate on the inside of the frame and can be taken out by using pallet knife to prize them out. Start with one of the longest beads first and leave the top bead until last.
2. Give the glass a little tap to loosen it if it doesn’t come out straight away, then the whole unit should slide out easily. Just make sure it falls towards you and not back out onto the ground below!
3. Clear any debris that has found its way into the frame with a brush. Add spacers at the bottom of the frame – these could be pieces of plastic.
4. Get your new sealed unit (make sure you measure the glass before you buy one so you know which size to get) and carefully take it out of the packaging. Look for the British Standard mark – that shows you the bottom of the glass.
5. Lift the glass into the frame, starting with the bottom first, and make sure that it fits square in the frame before taking the spacers out.
6. Use a little washing up liquid to spread along the beads to make it easier when you slide them back into the frame. If they simply push and clip back in, you can use something like a block of wood to help you push them in correctly. Put them back in reverse order to how you took them out.

Aluminium windows have a range of benefits that make them a great alternative to uPVC windows. Developments in technology have meant that modern aluminium windows now have the same energy efficiency levels as uPVC. Plus, their strength and flexibility make them a more attractive choice to many homeowners, particularly for more modern buildings.

Aluminium frames are typically much thinner than uPVC frames, allowing more light in and wider views. The metal can also be moulded to suit custom shapes, making it ideal for unusually shaped windows. Aluminium windows are available in lots of different colours, so can be designed to suit a wide range of interiors and exteriors.

After fitting your new windows, your installer should take away and dispose of your old windows. If you want to keep them, just let your installer know before they start work. The UPVC frames are melted down and used on the unseen parts of new windows. Aluminium frames are re-smelted and wooden are broken down and used as chipboard.